Cadaveric study of blood supply to the lower intraorbital fat: Etiologic relevance to the complication of anaerobic cellulitis in orbital floor fracture

Background and Purpose: Although orbital fractures are common, orbital cell ulitis rarely develops following orbital fracture. We hypothesized that com promise of the blood supply to the intraorbital fat during orbital floor fr acture is responsible for this condition. The purpose of this study was to determine whether or not the lower intraorbital fat is supplied by a branch of the infraorbital artery along the orbital groove or canal on the orbita l floor. Materials and Methods: We dissected 14 orbits from seven fixed human cadave rs and 12 orbits from six fresh cadaver heads following dye injection into the maxillary artery. The sires of dye-filled vessels branching from the in fraorbital artery supplying: the lower intraorbital fat were measured and p lotted on a two-dimensional orbital floor graph. Results: A main branch of the infraorbital artery rose through the medial o rbital floor to supply the lower intraorbital fat in all of the cadaver orb its. The sites of the branching point of the vessel ranged from 0 to 5 mm ( mean, 2.2 mm; n = 14) medial to the line connecting the infraorbital forame n and the infraorbital groove. The shortest distance measured from the bran ching point to the orbital rim ranged from 3 to 20 mm (mean. 14.1 mm; n = 1 4). This suggests that if orbital fracture were to occur around the infraor bital groove or canal, this vascular pedicle would be in danger of being in carcerated by bone fragments. Conclusion: Our cadaveric investigation revealed that the lower intraorbita l fat is supplied by a branch of the infraorbital artery along the infraorb ital groove or canal on the orbital floor. This finding suggests that compr omised blood supply to the intraorbital fat may cause anaerobic cellulitis or enophthalmos.